As much as we’ve so far been able to learn about how our early universe evolved, we still aren’t really sure how long the process took. Currently, there are two camps: those that look at the Cosmic Microwave Background and put the universe at 13.8 billion years with a nice slow 67 km/s/Mpc expansion, and those that look at supernovae and gravitationally lensed distant quasars and get an expansion of a zippy 74 km/s/Mpc, which implies a younger age. Since one of these camps looks at the first light of the universe and the other looks at the light from the past 11 billion years, it’s entirely possible that there is some physics that happens that we just don’t know that causes this discrepancy. Since no one wants to be wrong, however, teams keep doing new measurements and saying, no, we’re right. 

In recent news, we have confirmation of the Planck satellite’s measurements of the CMB that were made using the Atacama Cosmology Telescope to also look at the CMB. This work was led by Steve Choi and appears in the Journal of Cosmology and Astroparticle Physics. 

We also have news from gravitational wave astronomers admitting their data has enough inconsistencies that their measurements are consistent with both camps. This work appears in Physical Review Letters and is led by Hsin-Yu Chen. Meanwhile, the supernova and gravitational lens groups are consistent with each other and plugging away to demonstrate their accuracy even more.

Bottom line, we don’t know how old the universe is other than to say it is old, and if anyone tells you they know, ask them to explain both data from the first light and more recent light. If they can’t, they don’t actually know how old the universe is.

More Information

Cornell University press release 

“The Atacama Cosmology Telescope: a measurement of the Cosmic Microwave Background power spectra at 98 and 150 GHz,” Steve K. Choi et al., 2020 December 30, Journal of Cosmology and Astroparticle Physics

Center for Astrophysics article 

“Systematic Uncertainty of Standard Sirens from the Viewing Angle of Binary Neutron Star Inspirals,” Hsin-Yu Chen, 2020 November 12, Physical Review Letters